In grey forecasting model, there are two unsolved problem, the theoretical basis of transformation from discrete form to continuous form and the forecasting stability, which puzzled those who are absorbed in grey theory. Many scholars used all kinds of methods to revise the model, and they have made some progress, but they didn't solve it absolutely in principle. To solve these two problem and on the basis of the angle from discrete to discrete, discrete grey forecasting model(which is called DGM(1,1)) is constructed. And the relationship between it and original grey forecasting model is studied on, also the course of unstability in original grey forecasting model is found out. And it is explained by using DGM(1,1). Finally a series of accurative index number is used to prove the unbiased property of DGM(1,1). It is indicated that the simulative result is satisfied and DGM(1,1) can be considered as the precise form of grey forecasting model and original GM(1,1) as approximate form.
Systems Engineering—Theory & Practice